In the telecommunications equipment industry, new systems are developed to enhance the efficiency and reliability of communications services. These technologically advanced systems are ultimately deployed in the public-switched telephone network (PSTN) to provide subscribers with previously unavailable features. Evidence of the technological evolution occurring in the PSTN is the replacement of older, analog switches with digital switches. Organizations which operate private switches, such as private branch exchanges (PBXs), are often required to upgrade the PBX to reap the benefit of a technological advance. In some cases, these organizations are instead opting to abandon the older analog private branch exchange (PBX), and its associated high maintenance/upgrade cost. Indeed, many organizations which were previously sewed by PBXs now subscribe to services, such as Centrex and voice mail, provided by a local exchange carrier (LEC). Since the LECs are diligent in their efforts to provide the most advanced features to their customers, the formerly PBX-dependent organizations enjoy the option of subscribing to new features without investing in upgrades of their telecommunications switching equipment.
Although an investment in advanced customer premises equipment (CPE) is not usually required when an organization decides to replace an analog PBX with service from a LEC digital central office switch, there are some service features provided by the digital switch which are incompatible with certain types of CPE. Particularly, many hotels have older, guest room telephones equipped with a neon message lamp which indicates to the hotel guest that a telephone message is waiting for retrieval. Traditionally, the message lamp is illuminated by a 90 volt potential supplied by the hotel's private branch exchange via the guest room telephone line. Digital central office switches, however, provide a "waiting message" indication by delivering a frequency shift key (FSK) signaling message on an appropriate subscriber line to illuminate a light emitting diode (LED) "message waiting" light which is found on new "digital" telephone equipment. Indeed, continuously supplying 90 volts on a subscriber line to illuminate a neon message lamp found on older telephones would require an expensive modification to the digital switch, and would also pose a safety hazard for technicians working at the control office, who need to access the subscriber line for routine maintenance. Nevertheless, the inability of a service-oriented organization, such as a hotel, to automatically notify guests of waiting messages would result in guest inconvenience and frustration. Therefore, there is a need in the art for a cost-effective mechanism to safely activate a neon message lamp on existing customer premises equipment in response to signaling messages from a digital central office switch.